In the operation of pay telephones, it is important to be able to temporarily accept a coin pending the connection of the attempted telephone call. For example, if the telephone call is not completed, the coins are to be refunded. On the other hand, if the call does go through and is answered on the other end, the coins are accepted and passed to the coin receptacle or coin box.
An early example of a coin escrow mechanism is shown in U.S. Pat. No. 751,081 of Larned (patented in 1904). The '081 patent describes a coin-controlled telephone apparatus in which coins are deposited and either initially rejected along a coin return path or selectively captured temporarily subject to permanent collection upon the connection of the telephone call. The '081 patent describes that the control of the apparatus to accept or reject coins is effected by a remote telephone operator at a central switchboard.
U.S. Pat. No. 886,499 of J. Harrison discloses a pay telephone box with a coin acceptance mechanism using a V-shaped gate pivotally mounted in the coin chute at a point where the chute branches into a depositing chute and a return chute. As in the Larned patent, the '499 patent describes control by a remote operator who activates an actuator in the mechanism which deposits the coin into either of the desired chutes.
U.S. Pat. No. 1,098,673 of Lyng discloses a coin collector or coin escrow mechanism which uses a pivotal coin escrow door positioned beneath a coin hopper. The coin escrow door is supported by a pendulum arm which is pivoted from a position above the door. The pendulum arm has a roller at the bottom thereof for engaging a curved cam beneath the lower door and as the arm swings the roller in one direction, the lower door is allowed to tilt downwardly in an opposite direction. However, because the pendulum arm moves upwardly somewhat as it swings sideways, it tends to continue to hold the escrow door tightly closed until a substantial angular movement of the pendulum arm has been effected. Indeed, the curved cam of Lyng appears to have a radius of curvature closely matching the curvature of the pivotal motion of the roller about the pivot point of the pendulum arm, thereby maintaining a consistent upward force on the lower door until the pendulum arm is rotated enough to move the roller from between the pivot points about which the lower door is supposed to rotate. This requires that the pendulum arm be moved a substantial amount in order to release the coins from the hopper into one chute or the other. In fact, to ensure that the lower door eventually opens, a reverse bend is formed in the cam beyond the pivot points to force the door open once the roller has cleared the pivot points. Requiring such an exaggerated motion tends to require substantial power to actuate the mechanism.
U.S. Pat. No. 5,216,707 discloses a coin escrow unit which operates on the principles of a relay. The relay is designed to trip one way or another based on receiving a signal of positive 130 volts DC or negative 130 volts DC and based on there being a certain amount of current flowing. Thus, in order to trip the relay one way or the other, both a current criteria and a voltage criteria are to be met. In order to ensure that the relay trips one way or the other only when desired (and not when a simple coin test is being conducted to see if a coin has been received or not) mechanical adjustments of springs and tension on the springs must be made in the field to compensate for local conditions. This makes the manufacturing of a uniformly performing product extremely problematical and requires careful installation and frequent maintenance of the relay in order to ensure proper operation.
The coin escrow units just described generally have been designed to be used in conjunction with a coin operated pay telephone which is controlled by a central office. In this arrangement, the central office makes certain determinations to evaluation whether to accept or reject coins contained in the escrow unit or to return them to the user. More recently, it has become popular for a pay telephone to be customer-owned and coin-operated, the so-called customer-owned, coin-operated telephone (COCOT). In these arrangements, the control is effected locally, rather than through a central office. These types of phones are often called "smart phones" because the decision-making power is placed within the phone or nearby. Conventionally, operators of these types of phones have demanded a very high level of performance. In this regard, operators have found it necessary to ensure that the coin escrow unit is instructed properly to accept the coinage, to return the coinage, or to simply continue to hold on to the coinage. Operators of such telephones also require that the coin escrow unit provide physical confirmation that the coinage has been successfully returned or accepted. To accomplish this, prior art escrow designs designed for use with a "smart" telephone chassis have incorporated various flags, switches, relays, etc., to convert mechanical movement of part of the coin escrow unit into a signal which represents that the coin escrow unit has successfully accepted, or successfully returned, the coinage contained within the coin escrow unit. Unfortunately, this requirement that the system actually confirm that the coin escrow unit has properly fired has led to a complicated and costly mechanism for confirming the successful firing of the coin escrow unit.
Recently, Quadrum Telecommunications, Inc. of Huntsville, Ala. (assignee of the present application) has developed an improved coin escrow unit. The new improved coin escrow unit is described in co-pending U.S. patent application Ser. No. 08/903,448 (filed on Jul. 3, 1997) and has exhibited very high reliability and dependability rates, obviating the need for continual testing to see whether the coin escrow unit has successfully fired or not.
Unfortunately, such a coin escrow unit to be used with existing "smart" telephones, a problem exists in that the smart telephones seek a confirmation that the coin escrow mechanism has successfully fired. Although it would be possible to add the necessary eletromechanical components to test for and then generate an electrical signal indicative of successful firing of the coin escrow apparatus, this would inherently raise the level of complexity of the improved coin escrow apparatus and at the same time would raise the cost as well.
Accordingly, it can be seen that a need yet remains for a coin escrow apparatus having substantially improved reliability over prior art devices and which is compatable with the more recent "smart" telephones. It is to the provision of such a coin escrow apparatus that the present invention is primarily directed.